1. Field of the Invention
The claimed invention relates to a suction conduit switching apparatus for an endoscope that switches a conduit from a suction port at a tip of an endoscope insertion section and an endoscope.
2. Description of the Related Art
An endoscope is provided with a suction conduit that leads to a suction port at a tip in an insertion section which is inserted into a body of a patient. The suction conduit is connected to a suction conduit switching apparatus that is disposed in a hand operation unit. The suction conduit is also used as a treatment tool insertion channel that is used to insert a treatment tool such as a forceps. The suction conduit that branches from the middle of the treatment tool insertion channel is connected to the suction conduit switching apparatus in most cases.
A suction source conduit that leads to a suction source such as a suction pump and the suction conduit are connected to the suction conduit switching apparatus. Switching between a stand-by state where the suction source conduit and the suction conduit are blocked and a suctioning state where the suction source conduit and the suction conduit communicate with each other to allow suctioning can be performed by a pressing operation.
The suction conduit switching apparatus, examples of which include a suction button, is provided with a cylinder and a piston. In suction buttons in JP1995-008448A (JP-H07-008448A) and JP2004-223121A, a cylinder has a piston passage that has one open end, a suction connection port that is formed at the other end of the piston passage and leads to a suction conduit, and a suction source connection port that is formed in an inner peripheral surface of the piston passage and leads to a suction source conduit. A piston is inserted into the piston passage from the other end and is displaced from a first position to a second position by a pressing operation. An outer peripheral surface opening that communicates with the suction source connection port at the second position, the other end opening that is formed at the other end and communicates with the suction connection port, and a communication passage that allows the outer peripheral surface opening and the other end opening to communicate with each other are formed in the piston. When the piston is moved to the second position by pressing an operation cap that is fixed to the piston and the outer peripheral surface opening of the piston is allowed to communicate with the suction source connection port of the cylinder, the suction conduit and the suction source conduit communicate with each other and suctioning from a suction port is performed.
In an endoscope apparatus in JP2000-189380A, a suction amount is controlled in response to an operation cap pressing amount. According to JP2000-189380A, a rotation valve is subjected to rotation control via a motor so that a leak hole of a leak valve is closed by a predetermined amount and the suction amount is controlled or a rotating roller is subjected to rotation control. In this manner, pressing of a suction tube by a suction roller and a suction tube pressure plate is gradually opened so that the suction amount is controlled.